A +2.00-nC point charge is at the origin, and a second -5.00-nC point charge

A +2.00-nC point charge is at the origin, and a second -5.00-nC point charge is on the x-axis at x = 0.800 m.

(a) Find the electric field (magnitude and direction) at each of the following points on the x-axis:
(i) x = 0.200 m;
(ii) x = 1.20 m;
(iii) x = -0.200 m.
(b) Find the net electric force that the two charges would exert on an electron placed at each point in part (a).

This video explains it! What is (Fnet3)x, the x-component of the net force exerted by these two charges on a third charge q3 - YouTube